Just swim sideways or float. It’s so easy to float in the ocean and doesn’t take much energy. Most people panic, though, and don’t remember to do simple things. When I was in lifeguard training, most of the stuff they teach you is how to deal with completely irrational actions people do when panicking.

Also, never underestimate the ocean (or any moving water). I’ve been swimming, waterskiing, surfing, scuba diving, whitewater kayaking, sailing for over 40 years, and I’ve had a TON of instances of “oh shit, I have zero control over what the water is doing to me right now.” Just completely powerless as the ocean tosses you around or the river pulls you down behind a boulder and holds you until you can find the bottom and kick out of the “hole.”